This invention relates to a devise for producing pipe joints made of synthetic resin and formed with a groove in the inner peripheral surface for fitting a seal ring therein.
Pipe joints made of synthetic resin are typically manufactured by an injection molding process. Although such processes are suitable for producing a large quantity of pipe joints of the same shape, there are certain drawbacks to using injection molding to produce articles having deep undercut portions in the inner periphery of a cylindrical article to be produced. For example, a mold for producing a joint with an undercut portion requires an extremely complicated mechanism, and as a result the mold is expensive and the process of removing the core of the mold from the molded article is very onerous and is liable to cause trouble.